Fuel pump

Hi I'm new to this forum. I've got a 1983 glastron Carlson with a 470 mercruiser 3.7. I just bought it about 2 months ago I'm having issues with it starting. I checked the fuel line from the tank to the electric fuel pump and all is fine. From the pump to the carb no gas, I tried putting gas into the carb and the motor started for a second. I'm not familiar with wiring to much there's a red green light blue and black wire coming off the fuel pump and the black wire is cut and not hooked to anything. Can someone please help me with this

Ayuh,.... All the 470s came with mechanical fuel pumps,....

Someone may have added one, though. Can you post a photo of this "pump"?

Jeff